AT391496B - ROLL PRESS FOR THE TREATMENT OF RAIL-SHAPED GOODS, E.g. PAPER RAILS - Google Patents

Description

No. 391496

The invention relates to a roller press for the treatment of sheet-like goods, such as. B. paper webs, consisting of a stationary press roll and at least one arranged parallel to this, can be pressed by adjustment by means of positioning cylinders transversely to the longitudinal axis against the press roll and can be lifted off it by a device for automatically relieving the contact pressure between the press roll and the press roll as a result of a malfunction .

A roller press of the generic type is known from DE-PS 959 702, in connection with a plant for the production of paper and cellulose webs. In general, a roller press of the type mentioned can be used in wet presses and smoothing units in paper-making machines, but also in plastic calenders or rolling mills.

In the known roller press or plant for producing paper and cellulose webs, a device is provided for automatically lifting the pressure roller which can be pressed against a stationary suction roller. The lifting process is triggered by the fact that the pressure prevailing in the suction line of the suction roll exceeds a certain working pressure during operation of the roll press, i. that is, the required negative pressure is no longer present in the suction line. The printing roller is connected to a printing cylinder which is ultimately activated when drying of the paper web is no longer guaranteed

Short-term pressure fluctuations are not recognized in the known concept, and in particular spatially limited faults on the suction roll are not recognized because the air volume measurements in the suction lines are too imprecise for such deviations. Thus, z. B. entrained foreign bodies or folded areas of a drainage felt running through the press nip between the suction roller and the pressure roller undetected For the correct operation of such a roller press and for the protection of the expensive roller covers and drainage felts, it is extremely important to recognize even short-term and minor faults quickly and reliably.

The object on which the present invention is based is to specify a roller press of the generic type, in which relatively small faults are also recognized, very quickly, and in which, as a result of these faults, the press nip is immediately relieved over the entire width and, if necessary, also opened .

This object is achieved in that each positioning cylinder has a safety valve which, in the event of a pressure rise in the positioning cylinder, in particular as a result of a fault in the press nip between the press roll and the press roll, relaxes the pressure in the positioning cylinder, and in that the safety valves function with one another via at least one signal line are coupled that in the event of a pressure rise occurring on a positioning cylinder, the pressure in the other positioning cylinders is also relaxed.

Further developments of this given teaching are the subject of the dependent claims.

The invention is explained in more detail below with reference to the drawings, which show in

Figure 1 is an overall schematic representation of a three-roll wet press.

FIG. 2 shows an overall schematic representation of the hydraulic circuit for the three-roll wet press according to FIG. 1;

3 shows one of the safety valves shown in FIG. 2 in its second switching state;

FIG. 4 one of the safety valves shown in FIG. 2 in its design;

Fig. 5 shows a second embodiment of the hydraulic circuit for a two-roll press;

In Fig. 1, a so-called three-roll wet press is shown, as z. B. is known from DE-PS 1 090 076. For the sake of clarity of the illustration, the dewatering felts and the paper web to be dried as well as guide rollers, frame elements and other mechanical construction elements are not included in the drawing.

The three-roll wet press (1) shown consists of a press roll (3) which is fixedly mounted in immovable bearings (2) and two pressure rolls (4), (5) which can be applied tangentially. The longitudinal axes of the press roll (3) and the pressure rolls (4), (5) lie in one plane.

One pressure roller (4) - the lower one in the drawing - is placed against the weight roller (3) against its weight force via a first pair of levers (6), (7). The second pressure roller (5) is supported by its own weight force applied from above to the press roller (3) by means of a second pair of levers (8), (9). The levers (6), (7), (8), (9) are each fixedly supported on one side and are connected at the second end so as to be rotatable with the end faces of the pressure rollers (4), (5).

To actuate or move the levers, a positioning cylinder (10), (11), (12), (13) acts on each of these levers, via which the pressure rollers (4), (5) ultimately press the pressure roller with the required pressing force (3) can be pressed. The pressing force between the pressure rollers (4), (5) and the pressure roller (3) is determined by the working pressure in the positioning cylinders (10), (11), (12), (13)

The positioning cylinders (10), (11), (12), (13) each have an inlet (101), (102) on the piston side and on the rod side relative to the working or reciprocating piston; (111), (112); (121), (122); (131), (132) for the working medium, via which the working pistons are brought into the correct working position or to the correct pressure. In the three-roll wet press (1) shown in FIG. 1 and also in the two-roll press to be described with reference to FIGS. 5 and 6, each printing roll is assigned a positioning cylinder on the end side, so that the pressing force d. H. the working pressure between the press and pressure roller can be set precisely across the entire width of the roller section. -2-

No. 391496

Building on this constellation, the essence of the invention is to assign a safety valve to each of the positioning cylinders, via which a pressure rise identified in a positioning cylinder due to e.g. B. a malfunction in the press nip between a (the) pressure roller (s) and the press roller leads to a pressure relief of this positioning cylinder and the other Positionieizylinder this press section

In Fig. 2 the hydraulic diagram of the three-roll wet press is shown

The positioning cylinders (10), (11), (12), (13) are each assigned to a lever acting on the end faces of the pressure rollers, specifically in such a way that - cf. Fig. 1 - the positioning cylinder (10), (11) of a printing roller and the positioning cylinder (12), (13) correspond to the other printing roller. The positioning cylinders (10), (11) and (12), (13), which belong together in pairs, are together with their inlet (101), (111) or (121), (131) together with a main control valve (20) or (21) connected. The positioning cylinders (10), (11) and (12), (13) can be connected to an oil pump (22) and (23) via these main control valves (20), (21), which the positioning cylinders (10), ( 11) or (12), (13) via their inlets (101), (111) or (121), (131) with the required working pressure.

Each of the positioning cylinders (10), (11), (12), (13) is assigned a safety valve (24), (25), (26), (27), which is designed so that it is in the associated positioning cylinder (10), (11), (12), (13) occurring pressure increase, i. H. if an overpressure occurs, the pressure in this positioning cylinder (10), (11), (12), (13) is immediately released. The safety valves (24), (25), (26), (27) each of a press section are also coupled to one another such that an overpressure of the identified in one of the safety valves (24), (25), (26), (27) associated positioning cylinder (10), (11), (12), (13) is simultaneously forwarded to all other safety valves (24), (25), (26), (27) of the same press section, and this then also the associated positioning cylinder (10), (11), (12), (13) relax according to working pressure.

In the event of an overpressure occurring on a positioning cylinder (10), (11), (12), (13) (due to a fault in the adjacent press nip, for example), all the positioning cylinders are thus relieved. 1, this means that the lower pressure roller (4) moves downward due to its weight and opens the press nip; the upper pressure roller (5) should also be lifted, d. H. If the upper press nip is opened, the associated positioning cylinders (12), (13) are to be loaded on the piston rod side. With a working signal generated in one of the safety valves (10), (11), (12), (13) as a result of an overpressure state, other functions such as, for. B. shutdown of the press drive can be initiated.

The mode of operation and the structural design of a safety valve (24), (25), (26), (17) are explained in detail below:

The safety valve (24), (25), (26), (27) has two line connections (a), (b) on its input side, an axially movable valve body (30) and two connections (34) on its output side, (35). The latter are both connected to a relief line (33) which leads to an oil drip pan. The movable valve body (30) has a first end face (A1) and, opposite thereto, a somewhat smaller second end face (A2). The first end face (A1) and the connection (a) are connected to the inlet (101) of the cylinder (10) and therefore acted upon directly by its working pressure. The second, smaller end face (A2) and the connection (b) are also connected to the inlet (101) of the cylinder (10), but via a throttle (31). The second end face (A2) is additionally subjected to the force of a spring (32). (In the static state, i.e. as long as no oil flows through the throttle, the pressure on (Al) and (A2) is the same).

According to the illustration in FIG. 2, the valve bodies (30) of the safety valves (24), (25), (26), (27) are at the upper stop; the connections to the relief line (33) are interrupted, i. H. blocked.

As already mentioned, the safety valves (24), (25), (26), (27) of a press section are coupled to one another. According to the exemplary embodiment in FIG. 2, this is realized in such a way that the second end faces (A2) of all the safety valves (24), (25), (26), (27) are connected to one another via signal lines (36). In the event of an inadmissible pressure increase in the working pressure in one of the positioning cylinders (e.g. (10)), the pressure increase on the end face (A1) of the safety valve (24) triggers a displacement of the valve body (30) in the direction of " open " (down in the drawing). As a result, the pressure at the smaller end face (A2) is relieved in the safety valve (24) (by connecting the two connections (b) and (35)). At the same time, the smaller end faces of the other safety valves (25), (26) and (27) are relieved via the signal lines (36), so that these also open. The result is that the inlets (101), (111), (121), (131) are connected to the relief line (33) on all positioning cylinders (10), (11), (12) and (13).

The switchable connections between the pressure-side connections (a), (b) and the connections (34), (35) on the outlet side are indicated by the solid arrows in the valve body (30). If the valve body (30) is displaced from the equilibrium position (downward in the drawing) against the force of the spring (32) due to an overpressure or due to the difference in force on the first end face (A1) and the second end face (A2) First, the (first) passage (b-35) corresponding to the lower arrow is released, so that the pressure on the second end face (A2) drops towards zero. As a result, the valve body (30) is moved further with increased force and the (second) -3- corresponding to the upper arrow also opens

No. 391496

Passage (a-34), leaving the first passage (b-35) open.

The force of the spring (32) is set so that slightly below a threshold value or difference value which triggers the switching process of a safety valve (24), (25), (26), (27), the pressure on the two end faces (Al) and ( A2) Acting forces are in balance with each other. The force of the spring (32) corresponds to the product of the area difference between the end faces (Al) and (A2) and the working pressure. With this adjustment of the force of the spring (32) " floats " the valve body (30) of the safety valves (24), (25), (26), (27) in a still closed intermediate position and thus has a very short reaction, ie. H. Switching time. In order to get by with small spring forces, the ratio between the two end faces (active surfaces) (Al) and (A2) is only slightly larger than 1, preferably between 1.02 and 1.2.

Once the safety valve (24), (25), (26), (27) has opened, the connection between the connection (a) of the working pressure and the expansion line (33) only remains open to the extent that the first end face (Al) acting residual force corresponds to the force of the spring (32). This measure or constructive solution finally keeps the connection of the signal line (36) to the relaxation line (33) open, and it is thus excluded that the working pressure on the positioning cylinders (10), (11), (12), (13) unintentionally rebuilds. This is necessary to ensure that the working pressure does not build up before the cause of the pressure rise has been identified and remedied

To return to normal working condition, i.e. H. To have working pressure available on all positioning cylinders (10), (11), (12), (13), the main control valve (20) or (21) must first be brought into its zero position. The pressure acting on the first end face (A1) is thus brought to zero and the safety valves (24), (25), (26), (27), d. H. their valve bodies (30) are pushed into the closed position by the force of the spring (32); the valve body (30) rests against the upper end stop. Now the main control valve (20), (21) can be opened, i. H. the positioning cylinders (10), (11), (12), (13) can be subjected to working pressure again.

The switched-through state of the safety valve (24), (25), (26), (27) is shown on the basis of the functional diagram in FIG. 3.

According to this switching state, both the inlet (a) on the working pressure side and the second inlet (b) coupled via the throttle line (31) are connected to the expansion line (33). The connection from (b) to the relaxation line (33) is fully open; there is a throttled connection between the working pressure line (a) and the expansion line (33) because the force of the spring (32) maintains equilibrium. This means that the hydraulic fluid delivered by the oil pump (22) or (23) flows partly via the working pressure connection (a), partly via the throttled connection (b) to the expansion line (33).

The design of a safety valve (24), (25), (26), (27) is explained with reference to FIG. 4. This representation corresponds to a longitudinal section through this valve.

The safety valve essentially consists of a valve block (37), in which the valve body (30) is inserted so that it can move axially in a central bore (38). 4, the valve body (30) is located in the aforementioned "floating" Equilibrium position that it assumes when the working pressure is slightly below the set limit. This limit value is preferably chosen so that the difference between the pressure values at which the valve body lifts off the end stop and at which the pressure release begins z. B. 5% of the maximum permissible contact pressure between the pressure roller and the pressure roller

The valve body consists of two cylinders (39), (40) which are closed on one side and which, with their closed end faces, correspond to the active surfaces (A1) and (A2) of the safety valves (24), (25), (26), (27) 2 and 3 correspond to each other. The (upper) cylinder (39) with the larger diameter (Al) has access to the working pressure line (a) from its open side; the lower cylinder (40) with the smaller diameter (A2) has access from its open side to the inlet (b), which is connected via the throttle line (31) to the working pressure line (a).

According to another design, the two cylinders (39), (40) can also be combined in a one-piece valve body (30). Instead of the throttle line (31) arranged in the housing (37), a coaxial throttle bore can then be provided in the valve body (30).

The lower cylinder (40) is spring-mounted via a spring (32). The force of this spring (32) can be adjusted from the outside, specifically by means of a bolt (41) which is axially adjustable coaxially to the central bore (38). This bolt (41) has a support plate (42) corresponding to the diameter of the spring (32), which can be moved axially by means of a screw (43) and adjusts the spring (32) to the predetermined spring force.

Both cylinders (39), (40) each have openings (39 '), (40 *) distributed over the circumference, via which the line paths to the relaxation line (33) can be opened. For these line paths, two annular spaces (34), (35) are incorporated in the valve block (37) for the connections, which, according to FIGS. 2 and 3, both have a connection to the expansion line (33). The arrangement of these annular spaces (34), (35) or their assignment to the openings (39 '), (40') is such that with an axial movement (arrow (X)) of the valve body (30), d. H. of the two cylinders (39), (40) first have the openings (40 ') of the cylinder (40) with the smaller active surface / end surface (A2) to the lower annular space (35). With another move -4-

Claims (10)

No. 391496 of the valve body (30) then also opens the connection line between the working pressure line (a) and the expansion line (33) via the openings (39). The interaction with regard to the spring force and the result of the opening of the line paths (a) and (b) to the low-pressure line (33) has already been explained with reference to the functional diagram described in FIGS. 2 and 3. A second exemplary embodiment of the invention is explained below with reference to a two-roll press shown in FIG. 5. In contrast to the representations in and embodiments of FIGS. 2, 3 and 4, the example shown in FIG. 5 is an electrical system. From the outset, this has the advantage that the signal propagation is much faster, which can be important with regard to the rolls up to 10 m wide. Two positioning cylinders (10), (11) are provided for each printing roller, each of which is assigned an electromagnetic safety valve (50), (51). An electrical pressure switch (52), (53) is arranged on each positioning cylinder (10), (11) as a signal generator in the event that the working pressure in one of the positioning cylinders (10), (11) rises inadmissibly. If one of the pressure switches (52), (53) closes due to an impermissibly high pressure in one of the positioning cylinders (10), (11), the electromagnets of all safety valves (50), (51) are energized via the corresponding switching signal as the working signal. if these are signal-linked. At the same time, the safety valves (50), (51) are brought into an operating position in which a connection to a low-pressure connection, for example an oil drip pan, is activated. 5, this means the following: The safety valves (50), (51) each have an input port (c), which is connected to the working pressure-side port of the positioning cylinders (10) and (11) and via a main control valve (54) an oil pump (55) are connected. The safety valves (50), (51) consist of a valve body (56) or (57), which acts with the force of an electromagnet (58), (59) against the force of an adjusting spring (60), (61) in a first Operating position is maintained. In this first (drawn) operating position, the connection to be switched by the valve body is closed. The electromagnets (58), (59) are electrically supplied via a line (63) from a voltage source (62). The electromagnets (58), (59) are also connected to one another and to the pressure switches (52), via a signal line (64). (53) coupled. If a pressure switch (52), (53) is closed, the electromagnets (58), (59) become currentless. The valve bodies (56), (57) are pulled into their second operating position via their actuating springs (60), (61), as a result of which the inlet connection (c) is connected to the low-pressure line. The working pressure on the positioning cylinders (10), (11) thus drops to zero. (Of course, the switching can also take place in such a way that the electromagnets are de-energized when the valve is closed and are excited and open when the overload signal is given). As already explained with reference to FIG. 2, it must be prevented that the working pressure builds up prematurely and unintentionally. For this purpose, a hold circuit is integrated in the circuit, which ensures that the safety valves (50), (51) remain in the open state (second operating position). This holding circuit consists of a relay (65) which is parallel to the circuit of the electromagnets (58), (59) of the safety valves (50), (51) and can be acted upon by a switch (66) which can be switched to ground potential, so that the electromagnets (58), (59) are excited and pull the valve bodies (56), (57) against the force of the actuating springs (60), (61) into the first (closing) operating position. Working pressure on the positioning cylinders (10), (11) can now be built up again via the main control valve (54). PATENT CLAIMS 1. Roller press for the treatment of web-like goods, such as. B. paper webs, consisting of a stationary press roll and at least one arranged parallel to this, by pressing by means of positioning cylinders transversely to the longitudinal axis against the press roll and can be lifted off from it by a pressure roller with a device for automatically relieving the contact pressure between the press roller and the pressure roller due to a malfunction , characterized in that each positioning cylinder (10 to 13), in particular as a result of a fault in the press nip between the press roller (3) and the pressure roller (4), (5), relaxes the pressure in the positioning cylinder (10 to 13), and that Safety valves (24 to 27; 50, 51) are functionally coupled to one another via at least one signal line (36, 63) in such a way that when there is an increase in pressure on a positioning cylinder (10 to 13), the pressure in the other positioning cylinders (10 to 13 ) is relaxed. -5- No. 391496 2. Roller press according to claim 1, characterized in that the position cylinders (10 to 13) and the safety valves (24 to 27; 50, 51) of each pressure roller (4, 5) are assigned a main control valve (20, 21; 54) in such a way that that the closing of the main control valve triggers the closing of the safety valves (24 to 27; 50, 51) (e.g. by means of spring force (32)) for the purpose of returning to the normal operating state. 3. Roll press according to claim 1 or 2, characterized in that for opening the press nip with the own weight on the press roll (3) lying on the press roll (4) this can be raised on the basis of a work signal which, depending on one in one of the safety valves (24 to 27; 50, 51) identified pressure rise of a positioning cylinder (10 to 13) is generated. 4. Roller press according to one of claims 1 to 3, characterized in that the safety valve (10 to 13) in a manner known per se, a movable valve body (30) with a directly acted upon by the working pressure of the positioning cylinder (10 to 13) with a first pressure chamber first effective area (end face (Al)) and an opposite second pressure chamber with one of the first effective area (Al) opposite smaller second effective area (A2), which is acted upon by the force of a spring (32), the second pressure chamber via a throttle (31) with the pressure line (101, 111, 121, 131) of the working pressure and with a signal line (36), which connects the second pressure chambers of the safety valves (10 to 13) to each other, and the pressure chambers each with an outlet (34 , 35), to which a relief line (33) is connected, can be connected, the outlets (34, 35) being arranged relative to one another in such a way that when the pressure rises i n the pressure line (101 to 131) of the working pressure, first the second pressure chamber and thus the signal line (36) and then the first pressure chamber are connected to the low pressure line (33) (Fig. 2,3 and 4). 5. Roller press according to claim 4, characterized in that the force of the spring (32) is set so that at a given working pressure, the forces present at the active surfaces (A1, A2) of the pressure chambers are in equilibrium. 6. Roller press according to claim 5, characterized in that the ratio of the effective areas (Al, A2) of the first and the second pressure chamber is approximately 1.02 to 1.2. 7. Roll press according to claim 5 or 6, characterized in that the outlet (34) of the first pressure chamber and the outlet (35) of the second pressure chamber are arranged and dimensioned relative to one another such that after a relaxation of the working pressure, the outlet (34) of the first pressure chamber is opened so far that the pressure force acting on the first surface (A1) is equal to the force of the spring (32). 8. Roll press according to one of claims 4 to 7, characterized in that a valve body (37) with a central bore (38) for receiving two respectively one pressure chamber corresponding one-sided closed cylinder (39) (40) is provided that the cylinder (39), (40) with their closed end faces (Al), (A2) adjoining one another in the central bore (38) so that they can move axially so that the cylinders (39), (40) extend over one side of the valve body (37 ) forth adjustable spring (32) are supported such that the valve body (37) in the region of the open end faces of the cylinders (39, 40) each has an inlet bore (a, b) connected to one another via a throttle line (31), one of which is the cylinder (39) with the larger effective area (A1) with the pressure line for the working pressure and the second connecting the second cylinder (40) with the signal line (b, 36) that along the wall of the central bore (38) two annular spaces (41, 42nd ) are incorporated, the are connected to an outlet bore that can be connected to the expansion line (33), and that outlet openings (39 ', 40') are provided in the cylinders (39, 40) for the first and the second pressure chamber, which are provided during an axial movement of the cylinders (39, 40) overlap with the annular spaces (41, 42). 9. Roll press according to one of claims 1 to 3, characterized in that the safety valve (50, 51) is an electromagnetically actuated valve which is closed in one operating position (rest position) and which in the second operating position (working position) the pressure line of the Working pressure connects to a relief line that the safety valve (50, 51) is assigned an electrical pressure switch (52,53), which generates a work signal when the pressure in the Positionieizylindem increases, which the safety valve (50,51) from the rest position to the working position switches. 10. Roller press according to claim 9, characterized in that for holding the safety valves (50, 51) in the working state, a relay (65) connected to the working signal is provided, and that the relay (65) is assigned a switch (66) via which the relay (65) can be reset. Including 4 sheets of drawings -6-